Situations vacant for eagle-eyed stardust spotters

Stardust@home is now recruiting

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The University of California, Berkeley, is looking for eagled-eyed space buffs to search for minute particles which may or may not be, right now, on their way to Earth aboard interstellar dust catcher "Stardust" (seen right).

The Stardust mission spent seven years collecting dust from both the tail of comet Wild 2 and, subsequently, from interstellar space. Its Stardust Interstellar Dust Collector hopefully trapped particles - travelling at 12 miles (20km) per second - in a silicon-based sponge called "aerogel", arranged in a disk-shaped mosaic of tiles about 16 inches in diameter and half-an-inch thick.

The vehicle's payload is due to parachute gently to Earth in Utah's Salt Lake desert on 15 January. It will be flown to Houston where "teams will open it so as to minimize contamination from other dust", as the press release explains.

Andrew Westphal, a UC Berkeley senior fellow and associate director of the campus' Space Sciences Laboratory, said: "These will be the very first contemporary interstellar dust grains ever brought back to Earth for study. Stardust is not only the first mission to return samples from a comet, it is the first sample-return mission from the galaxy."

According to Earth-based tests on the aerogel, the dust will have made carrot-shaped trails in the material, and Westphal reckons that while there will be "thousands of cometary dust grains embedded in the front of the detector, finding the 45 or so grains of interstellar dust stuck in the back of the detector won't be so easy". Accordingly, he has "developed an automated microscope to digitally photograph the entire area of the aerogel in patches that can be viewed later in search of dust particles".

Which is where you lot come in. Westphal and his colleagues have "created a 'virtual microscope' that will allow anyone with an internet connection to scan some of the 1.5 million pictures of the aerogel for tracks left by speeding dust. Each picture will cover an area smaller than a grain of salt."

The project, dubbed Stardust@home, is due to kick off in March. Westphal estimates some 30,000 person hours to scan all of the images at least four times. Sounds pretty straightforward, but the scientists warn: "Searching each picture should take just a few seconds, but the close attention required as the viewer repeatedly focuses up and down through image after image will probably limit the number a person can scan in one sitting."

What's more, "volunteer scanners must pass a test where he or she is asked to find the track in a few test samples", after which the volunteer's reliability will be tested as the team "throws in some ringers with and without tracks", or, as Westphal more scientifically explained it: "We will throw in some calibration images that allow us to measure the volunteer's efficiency."

The checks continue thus:

If at least two of the four volunteers viewing each image report a track, that image will be fed to 100 more volunteers for verification. If at least 20 of these report a track, UC Berkeley undergraduates who are expert at spotting dust grain tracks will confirm the identification. Eventually, the grain will be extracted* for analysis.

The reward for a hit after all this positive vetting and double-checking? The discoverers will be able to name their grains, which is nice.

The point of all this gel-probing is that Westphal hopes the information will "tell about the internal processes of distant stars - such as supernovas, flaring red giants or neutron stars - that produce interstellar dust and also generate the heavy elements - such as carbon, nitrogen and oxygen - necessary for life".

There's more general info on the Stardust@home website. Happy hunting. ®

Bootnote

You've got to admire the nerve, but NASA sent Stardust on its way in 1999 without having the faintest idea how to get the dust out of the aerogel. Apparently, though, it's all sorted now with Westphal and a chap called Chris Keller having developed "microtweezers" and "micro-pickle forks" to gently tease the stuff from the collector. Good show.